This Program Project asks: Can dietary restriction (DR), long known to retard aging and diseases in rodents, do so in nonhuman primates? Our hypothesis is that DR will similarly retard aging in a primate species, as reflected by attenuated rates of change of most biological indicators of aging and increased health span and life span. Two overall Specific Aims continue to be addressed. Sp. Aim 1 is to contribute to the development of the rhesus monkey as a model for the study of aging. Our longitudinal study should lead to an improved understanding of biological aging in this model. Ongoing study of conventionally-fed animals from our large aging colony will be continued as will investigation of three Groups of DR and Control rhesus monkeys, all of which were young adults (-10 yrs. old) when entering the study. Group 1 (n=15/group, males) began in 1989 with R01 funding. In 1994, with PPG support, we added 46 animals to increase statistical power for the key outcome measures on health span and life span. These were Group 2 (n = 15/group, females) and Group 3 (n = 8/group, males). These three Groups allow us to address Sp. Aim 2: to determine the influence of DR on the rate of aging in a primate species. [unreadable] [unreadable] This PPG's three Projects depend on the two Cores (Core A: "Administrative & Biostatistical Support"; Core B: "Animal Health and Sample Procurement"). Our highest priority is to determine health span, functionality and life span in these monkeys. Each of our projects has been designed to address this goal and characterize multiple features in the progression of age and effect of DR. Project 1, ("Role of DR-induced Metabolic Alterations in Sarcopenia") expands our studies to explore a mechanistic hypothesis that an adjustment of energy metabolism with DR is a major mechanism in aging retardation. Project 2 ("Energy Balance and Metabolism") will continue to probe relationships among age, DR, body composition (with an emphasis on adipose tissue), and energy expenditure and metabolism. Project 4 ("Brain Structure and Function") combines MRI and behavioral studies to explore the relationship between cerebral and cognitive changes with age and DR. [unreadable] [unreadable] The proposed work which utilizes the outstanding Primate Center and this precious animal resource will extend our 16-year-long study of aging and DR, an issue at the heart of gerontology and of widespread interest to the general populace. [unreadable] [unreadable]